Selection by higher‐order effects of salinity and bacteria on early life‐stages of Western Baltic spring‐spawning herring

Poirier, Maude; Listmann, Luisa; Roth, Olivia

doi:10.1111/eva.12477

Cited by 12 publications

(15 citation statements)

References 75 publications

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“…The adaptation to low-salinity conditions was even clearer at 35 psu, where fertilization rates of hybrids originating from 16 psu were very low (< 20%). This is consistent with a recent study of Poirier et al (2017), which also suggested that local adaptation to low salinity depends on the paternal origin. In contrast to their results, however, the hatching rates in our study were not influenced by any paternal or maternal origin or environmental conditions.…”

Section: Discussionsupporting

confidence: 93%

Genetic origin and salinity history influence the reproductive success of Atlantic herring

Berg¹,

Slotte²,

Andersson³

et al. 2019

Mar. Ecol. Prog. Ser.

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Atlantic herring populations inhabit environments ranging in salinity from fully marine to nearly freshwater, but their relative reproductive success in these respective environments remains unclear. We conducted factorial crossing experiments using parents from 3 wild populations associated with different salinity environments: the Baltic Sea (~6 psu), an inland brackish lake in Norway (Landvikvannet, ~16 psu), and the Atlantic (~30 to 35 psu). Further experiments used crosses within and between Atlantic purebreds and Atlantic/Baltic hybrids reared until first maturity at 3 yr of age. Crossing experiments were conducted at 6, 16 and 35 psu. Fertilization and hatching rates were estimated, and egg sizes were measured. Fertilization rates were highest at 16 psu for all combinations. The paternal genetic and salinity origin influenced fertilization rates at 6 and 35 psu, indicating a genetic adaptation to their original environment. Fertilization rates for males originating from 16 psu were low at 35 psu. Atlantic/Baltic hybrids had lower fertilization rates than Atlantic purebreds at 35 psu. Hatching rates were not influenced by any parental factors or salinity. Maternal effects and salinity influenced egg size. Atlantic females had significantly larger eggs than the Atlantic/Baltic hybrid females. For all genetic groups, egg size decreased with increasing salinity at incubation mainly due to osmotic effects. The observed lower fertilization success at salinities other than those of the parental fish habitat would have evolutionary consequences when herring colonize new habitats with different salinities or if interbreeding occurred between populations originating from different salinity habitats.

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Section: Discussionsupporting

confidence: 93%

Genetic origin and salinity history influence the reproductive success of Atlantic herring

Berg¹,

Slotte²,

Andersson³

et al. 2019

Mar. Ecol. Prog. Ser.

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“…V. alginolyticus, a ubiquitous marine opportunistic pathogen can cause mass mortalities in shellfish, shrimp, and fish, resulting in severe economic losses worldwide [3,21,22]. Vibrio pathogenicity is a complex interaction of abiotic and biotic factors, including high temperatures [23,24] low salinities [25], host and bacterial genotypes [26,27]. To date only six closed alginolyticus genomes are available, while 28 remain fragmented with 2 to 75 contigs (last accessed: December 2019).…”

Section: Introductionmentioning

confidence: 99%

Genomic variation among closely related Vibrio alginolyticus strains is located on mobile genetic elements

et al. 2020

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Background: Species of the genus Vibrio, one of the most diverse bacteria genera, have undergone niche adaptation followed by clonal expansion. Niche adaptation and ultimately the formation of ecotypes and speciation in this genus has been suggested to be mainly driven by horizontal gene transfer (HGT) through mobile genetic elements (MGEs). Our knowledge about the diversity and distribution of Vibrio MGEs is heavily biased towards human pathogens and our understanding of the distribution of core genomic signatures and accessory genes encoded on MGEs within specific Vibrio clades is still incomplete. We used nine different strains of the marine bacterium Vibrio alginolyticus isolated from pipefish in the Kiel-Fjord to perform a multiscale-comparative genomic approach that allowed us to investigate [1] those genomic signatures that characterize a habitat-specific ecotype and [2] the source of genomic variation within this ecotype. Results: We found that the nine isolates from the Kiel-Fjord have a closed-pangenome and did not differ based on core-genomic signatures. Unique genomic regions and a unique repertoire of MGEs within the Kiel-Fjord isolates suggest that the acquisition of gene-blocks by HGT played an important role in the evolution of this ecotype. Additionally, we found that~90% of the genomic variation among the nine isolates is encoded on MGEs, which supports ongoing theory that accessory genes are predominately located on MGEs and shared by HGT. Lastly, we could show that these nine isolates share a unique virulence and resistance profile which clearly separates them from all other investigated V. alginolyticus strains and suggests that these are habitat-specific genes, required for a successful colonization of the pipefish, the niche of this ecotype. Conclusion: We conclude that all nine V. alginolyticus strains from the Kiel-Fjord belong to a unique ecotype, which we named the Kiel-alginolyticus ecotype. The low sequence variation of the core-genome in combination with the presence of MGE encoded relevant traits, as well as the presence of a suitable niche (here the pipefish), suggest, that this ecotype might have evolved from a clonal expansion following HGT driven niche-adaptation.

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“…Marine bacteria of the genus Vibrio are present along the coast of the Baltic Sea [20,21] and their abundance, genetic composition and virulence are related to environmental factors, including temperature and salinity [20,22,23]. Characteristic for this habitat is a salinity gradient ranging from almost freshwater in the North and East to nearly fully marine conditions at the transition to the North Sea [24].…”

Section: Introductionmentioning

confidence: 99%

Filamentous phages reduce bacterial growth in low salinities

2019

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Being non-lytic, filamentous phages can replicate at high frequencies and often carry virulence factors, which are important in the evolution and emergence of novel pathogens. However, their net effect on bacterial fitness remains unknown. To understand the ecology and evolution between filamentous phages and their hosts, it is important to assess (i) fitness effects of filamentous phages on their hosts and (ii) how these effects depend on the environment. To determine how the net effect on bacterial fitness by filamentous phages changes across environments, we constructed phage–bacteria infection networks at ambient 15 practical salinity units (PSU) and stressful salinities (11 and 7 PSU) using the marine bacterium, Vibrio alginolyticus and its derived filamentous phages as model system. We observed no significant difference in network structure at 15 and 11 PSU. However, at 7 PSU phages significantly reduced bacterial growth changing network structure. This pattern was mainly driven by a significant increase in bacterial susceptibility. Our findings suggest that filamentous phages decrease bacterial growth, an indirect measure of fitness in stressful environmental conditions, which might impact bacterial communities, alter horizontal gene transfer events and possibly favour the emergence of novel pathogens in environmental Vibrios.

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Selection by higher‐order effects of salinity and bacteria on early life‐stages of Western Baltic spring‐spawning herring

Cited by 12 publications

References 75 publications

Genetic origin and salinity history influence the reproductive success of Atlantic herring

Genetic origin and salinity history influence the reproductive success of Atlantic herring

Genomic variation among closely related Vibrio alginolyticus strains is located on mobile genetic elements

Filamentous phages reduce bacterial growth in low salinities

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